Add align to struct mg_iobuf

src/iobuf.c

@@ -10,8 +10,13 @@ static void zeromem(volatile unsigned char *buf, size_t len) {
   }
 }
 
+static size_t roundup(size_t size, size_t align) {
+  return align == 0 ? size : (size + align - 1) / align * align;
+}
+
 int mg_iobuf_resize(struct mg_iobuf *io, size_t new_size) {
   int ok = 1;
+  new_size = roundup(new_size, io->align);
   if (new_size == 0) {
     zeromem(io->buf, io->size);
     free(io->buf);
@@ -36,21 +41,18 @@ int mg_iobuf_resize(struct mg_iobuf *io, size_t new_size) {
   return ok;
 }
 
-int mg_iobuf_init(struct mg_iobuf *io, size_t size) {
+int mg_iobuf_init(struct mg_iobuf *io, size_t size, size_t align) {
   io->buf = NULL;
+  io->align = align;
   io->size = io->len = 0;
   return mg_iobuf_resize(io, size);
 }
 
 size_t mg_iobuf_add(struct mg_iobuf *io, size_t ofs, const void *buf,
-                    size_t len, size_t chunk_size) {
-  size_t new_size = io->len + len;
-  if (new_size > io->size) {
-    new_size += chunk_size;             // Make sure that io->size
-    new_size -= new_size % chunk_size;  // is aligned by chunk_size boundary
-    mg_iobuf_resize(io, new_size);      // Attempt to realloc
-    if (new_size != io->size) len = 0;  // Realloc failure, append nothing
-  }
+                    size_t len) {
+  size_t new_size = roundup(io->len + len, io->align);
+  mg_iobuf_resize(io, new_size);      // Attempt to resize
+  if (new_size != io->size) len = 0;  // Resize failure, append nothing
   if (ofs < io->len) memmove(io->buf + ofs + len, io->buf + ofs, io->len - ofs);
   if (buf != NULL) memmove(io->buf + ofs, buf, len);
   if (ofs > io->len) io->len += ofs - io->len;